MacBook - Upgrading hard disk

Hi,
I'm looking to upgrade my macbook's memory to around 320GB. At the moment I'm still running on 120 and have well and truly run out

Just got a couple of queries. Firstly, am I right in assuming there's no way of actually upgrading the size of the existing one, or is the only way to buy a new one.
Secondly, if that is the case, will all of my programs be installed again. I ask this because I've ran out of uploads on my Logic pro and Adobe packages, so would like very much to not have to splash out again!!

If you want to keep every thing you will need to clone your current hard drive

My suggestion is to get a cheap external enclosure USB SATA (20$)
put your new hard drive in it (yes you will need a new hard drive).. and Use SuperDuper to clone your existing
hard drive. it is very simple and straight forward to use.